Improving the reliability of the iron concentration quantification for iron oxide nanoparticle suspensions: a two-institutions study.

Most iron oxide nanoparticles applications, and in special biomedical applications, require the accurate determination of iron content as the determination of particle properties from measurements in dispersions is strongly dependent on it. Inductively coupled plasma (ICP) and spectrophotometry are two typical worldwide used analytical methods for iron concentration determination. In both techniques, precise determination of iron is not straightforward and nanoparticle digestion and dilution procedures are needed prior to analysis. The sample preparation protocol has been shown to be as important as the analytical method when accuracy is aimed as many puzzling reported results in magnetic, colloidal, and structural properties are simply attributable to inadequate dissolution procedures. Therefore, a standard sample preparation protocol is needed to ensure the adequate and complete iron oxide nanoparticle dissolution and to harmonize this procedure. In this work, an interlaboratory evaluation of an optimized iron oxide nanoparticle digestion/dilution protocol was carried out. The presented protocol is simple, inexpensive, and does not involve any special device (as microwave, ultrasound, or other high-priced digestion devices). Then, iron concentration was measured by ICP-OES (performed in ICMM/CSIC-Spain) and spectrophotometry (NanoPET-Germany) and the obtained concentration values were analyzed to determine the most probable error causes. Uncertainty values as low as 1.5% were achieved after the optimized method was applied. Moreover, this article provides a list of recommendations to significantly reduce uncertainty in both sample preparation and analysis procedures. Graphical abstract ᅟ.

Bismuth labeling for the CT assessment of local administration of magnetic nanoparticles.

Many therapeutic applications of magnetic nanoparticles involve the local administration of nanometric iron oxide based materials as seeds for magnetothermia or drug carriers. A simple and widespread way of controlling the process using x-ray computed tomography (CT) scanners is desirable. The combination of iron and bismuth in one entity will increase the atenuation of x-rays, offering such a possibility. In order to check this possibility core-shell nanocrystals of iron oxide@bismuth oxide have been synthesized by an aqueous route and stabilized in water by polyethylene glycol (PEG), and we have evaluated their ability to generate contrast by CT and magnetic resonance imaging (MRI) to measure the radiopacity and proton relaxivities using phantoms. High-resolution scanning transmission electron microscopy (STEM) revealed that the material consists of a highly crystalline 8 nm core of maghemite and a 1 nm shell of bismuth atoms either isolated or clustered on the nanocrystal's surface. The comparison of µCT and MRI images of mice acquired in the presence of the contrast shows that when local accumulations of the magnetic nanoparticles take place, CT images are more superior in the localization of the magnetic nanoparticles than MRI images, which results in magnetic field inhomogeneity artifacts.

Synthesis methods to prepare single- and multi-core iron oxide nanoparticles for biomedical applications.

We review current synthetic routes to magnetic iron oxide nanoparticles for biomedical applications. We classify the different approaches used depending on their ability to generate magnetic particles that are either single-core (containing only one magnetic core, i.e. a single domain nanocrystal) or multi-core (containing several magnetic cores, i.e. single domain nanocrystals). The synthesis of single-core magnetic nanoparticles requires the use of surfactants during the particle generation, and careful control of the particle coating to prevent aggregation. Special attention has to be paid to avoid the presence of any toxic reagents after the synthesis if biomedical applications are intended. Several approaches exist to obtain multi-core particles based on the coating of particle aggregates; nevertheless, the production of multi-core particles with good control of the number of magnetic cores per particle, and of the degree of polydispersity of the core sizes, is still a difficult task. The control of the structure of the particles is of great relevance for biomedical applications as it has a major influence on the magnetic properties of the materials.

Structural determination of Bi-doped magnetite multifunctional nanoparticles for contrast imaging.

To determine with precision how Bi atoms are distributed in Bi-doped iron oxide nanoparticles their structural characterization has been carried out by X-ray absorption spectroscopy (XAS) recorded at the K edge of Fe and at the L3 edge of Bi. The inorganic nanoparticles are nominally hybrid structures integrating an iron oxide core and a bismuth oxide shell. Fe K-edge XAS indicates the formation of a structurally ordered, non-stoichiometric magnetite (Fe3-δO4) phase for all the nanoparticles. The XAS spectra show that, in the samples synthesized by precipitation in aqueous media and laser pyrolysis, the Bi atoms neither enter into the iron oxide spinel lattice nor form any other mixed Bi-Fe oxides. No modification of the local structure around the Fe atoms induced by the Bi atoms is observed at the Fe K edge. In addition, contrary to expectations, our results indicate that the Bi atoms do not form a well-defined Bi oxide structure. The XAS study at the Bi L3 edge indicates that the environment around Bi atoms is highly disordered and only a first oxygen coordination shell is observed. Indefinite [BiO6-x(OH)x] units (isolated or aggregated forming tiny amorphous clusters) bonded through hydroxyl bridges to the nanoparticle, rather than a well defined Bi2O3 shell, surround the nanoparticle. On the other hand, the XAS study indicates that, in the samples synthesized by thermal decomposition, the Bi atoms are embedded in a longer range ordered structure showing the first and second neighbors.

Biodistribution and pharmacokinetics of uniform magnetite nanoparticles chemically modified with polyethylene glycol.

The influence of polyethylene glycol (PEG) grafting on the pharmacokinetics, biodistribution and elimination of iron oxide nanoparticles is studied in this work. Magnetite nanoparticles (12 nm) were obtained via thermal decomposition of an iron coordination complex as a precursor. Particles were coated with meso-2,3-dimercaptosuccinic acid (DMSA) and conjugated to PEG-derived molecules by 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide (EDC) chemistry. Using a rat model, we explored the nanoparticle biodistribution pattern in blood and in different organs (liver, spleen and lungs) after intravenous administration of the product. The time of residence in blood was measured from the evolution of water proton relaxivities with time and Fe analysis in blood samples. The results showed that the residence time was doubled for PEG coated nanoparticles and consequently particle accumulation in liver and spleen was reduced. Post-mortem histological analyses showed no alterations in the liver and confirm heterogeneous distribution of NPs in the organ, in agreement with magnetic measurements and iron analysis. Finally, by successive magnetic resonance images we studied the evolution of contrast in the liver and measured the absorption, time of residence and excretion of nanoparticles in the liver during a one month period. On the basis of these results we propose different metabolic routes that determine the fate of magnetic nanoparticles.

Short-chain PEG molecules strongly bound to magnetic nanoparticle for MRI long circulating agents.

This study developed an approach for the synthesis of magnetic nanoparticles coated with three different polyethylene glycol (PEG)-derived molecules. The influence of the coating on different properties of the nanoparticles was studied. Magnetite nanoparticles (7 and 12 nm in diameter) were obtained via thermal decomposition of a coordination complex as an iron precursor to ensure nanoparticle homogeneity in size and shape. Particles were first coated with meso-2,3-dimercaptosuccinic acid by a ligand exchange process to remove oleic acid, followed by modification with three distinct short-chain PEG polymers, which were covalently bound to the nanoparticle surface via 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride activation of the carboxylic acids. In all cases, colloidal suspensions had hydrodynamic sizes <100 nm and low surface charge, demonstrating the effect of PEG coating on the aggregation properties and steric stabilization of the magnetic nanoparticles. The internalization and biocompatibility of these materials in the HeLa human cervical carcinoma cell line were tested. Cells preincubated with PEG-coated iron nanoparticles were visualized outside the cells, and their biocompatibility at high Fe concentrations was demonstrated using a standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Finally, relaxivity parameters (r1 and r2) were used to evaluate the efficiency of suspensions as magnetic resonance imaging contrast agents; the r2 value was similar to that for Resovist and up to four times higher than that for Sinerem, probably due to the larger nanoparticle size. The time of residence in blood of the nanoparticles measured from the relaxivity values, and the Fe content in blood was doubled for rats and rabbits due to the PEG on the nanoparticle surface. The results suggest that this PEGylation strategy for large magnetic nanoparticles (>10nm) holds promise for biomedical applications.

Size dependent allotropic transition of Co fine particles.

In order to investigate the size dependent allotropic transition of Co in wide size range, nanometer scaled (9 nm-350 nm) and micrometer sized (1 microm-18 microm) Co particles were prepared by laser induced pyrolysis, reduction as well as high temperature annealing treatment. In wide size range, from 9 nm to 10 microm for example, the crystal structure of the Co particles is dependent on their thermal history in which the particle involved in preparation or in annealing treatment. Only when the particle size is very large, much greater than 10 microm for example, the fcc-hcp transformation could occur during the cooling from high temperautre. According to the effect of surface energy on the martensitic transformation, the size dependent allotropic transformation of Co was discussed.

Functionalisation of glass with iron oxide nanoparticles produced by laser pyrolysis.

In the present work, a new process for depositing nanoparticle layers onto glass has been developed by using one of the most interesting nanoparticle generation technologies at the moment, which is based on the pyrolysis induced by laser of vapours combined with CVD of the particles onto glass. Nanoparticles prepared by this method were deposited into a hot silica substrate obtaining new nanocomposites with unique properties. The coated glasses present new specific functionalities such as colour, and interesting magnetic and optical properties. Control of the thickness and the iron oxide phase, either magnetic or not, has been achieved by adjusting the experimental conditions. Thus, thickness is controlled by the glass and the precursor temperature, while the iron phase is controlled by the precursor temperature and the nature and the flow of the carrier gas. This process is inexpensive, adaptable to current glass production technologies and takes place at atmospheric pressure.

Asymmetric chiral growth of micron-size NaClO3 crystals in water aerosols.

We describe an aerosol-liquid cycle that launches the autocatalytic amplification of any initial imbalance of the order of 10(-7)% (1 ppb) up to total chiral purity in a single step process. Crystal nucleation of NaClO3 is initiated at the aerosol air-water interface where, due to the accumulation of ambient chiral impurities or added hydrophobic chiral aminoacids in tiny concentrations (ppb), the initial levorotatory (l) and dextrorotatory (d) excess will not be produced with equal probability. The enantiomeric yield is then enhanced up to homochirality by recycling the crystallites through a liquid phase. In the absence of added catalysts this process leads to preferential (d) homochiral crystallizations in a ratio of 4:1 which is due to ambient contamination. By adding only 2 ppb of (L) or (D) Phe, we induce a final preferential homochiral crystallization of (d) or (l) handedness, respectively, in a ratio of 2:1.

The effects of ferrous and other ions on the abiotic formation of biomolecules using aqueous aerosols and spark discharges.

It has been postulated that the oceans on early Earth had a salinity of 1.5 to 2 times the modern value and a pH between 4 and 10. Moreover, the presence of the banded iron formations shows that Fe(+2) was present in significant concentrations in the primitive oceans. Assuming the hypotheses above, in this work we explore the effects of Fe(+2) and other ions in the generation of biomolecules in prebiotic simulation experiments using spark discharges and aqueous aerosols. These aerosols have been prepared using different sources of Fe(+2), such as FeS, FeCl(2) and FeCO(3), and other salts (alkaline and alkaline earth chlorides and sodium bicarbonate at pH = 5.8). In all these experiments, we observed the formation of some amino acids, carboxylic acids and heterocycles, involved in biological processes. An interesting consequence of the presence of soluble Fe(+2) was the formation of Prussian Blue, Fe(4)[Fe(CN)(6)](3), which has been suggested as a possible reservoir of HCN in the initial prebiotic conditions on the Earth.

Continuous production of water dispersible carbon-iron nanocomposites by laser pyrolysis: application as MRI contrasts.

Carbon encapsulated iron/iron-oxide nanoparticles were obtained using laser pyrolysis method. The powders were processed to produce stable and biocompatible colloidal aqueous dispersions. The synthesis method consisted in the laser decomposition of an aerosol of ferrocene solution in toluene. This process generated, in a continuous way and in a single step, a nanocomposite formed by amorphous carbon nanoparticles of 50-100 nm size in which isolated iron based nanoparticles of 3-10 nm size are located. The effect of using different carriers and additives was explored in order to improve the efficiency of the process. The samples after purification by solid-liquid extraction with toluene, were oxidised in concentrated nitric acid solution of sodium chlorate, washed and finally ultrasonically dispersed in 1 mM tri-sodium citrate solutions. The dispersions obtained have hydrodynamic particle size less than 150 nm and are stable in the pH range of 2-11. Finally the shortening of the transversal relaxation time of water protons produced by the dispersed particles was studied in order to test the feasibility of these systems to be traced by magnetic resonance imaging techniques.

Prebiotic microreactors: a synthesis of purines and dihydroxy compounds in aqueous aerosol.

We report the synthesis of purine bases and other heterocycles and the formation of amino acids, hydroxy acids and dihydroxy compounds by the spark activation of an atmosphere of methane, nitrogen and hydrogen, in the presence of an aqueous aerosol. With the aid of the interface air-water, the organic material obtained shows greater amounts and diversity of molecules with biological interest than the products obtained in the absence of an aerosol. Our results support the suggestion that aerosols may have played a significant role in the prebiotic origin of molecular diversity and evolution.

[Age and fertility: value of endometrial co-cultures]. / Age et fertilité: apport des cocultures sur cellules endométriales.

Embryo coculture system may contribute to understand the mechanisms underlying the decrease of fertility with aging. We report here our experience of coculture on maternal endometrial cells and histology of endometrial biopsy in 90 patients with repeated failures of implantation. Histology dating failed to find any age related changes. In coculture system, it is obvious that embryo viability diminishes with aging, but for equal embryonic quality, the maternal age does not interfere significantly on pregnancy rate. Anyway the number of first trimester abortions seems higher in older women. Coculture system emphasizes the major role of oocyte aging in the decrease of fertility and may be useful to establish a prognostic in IVF for older patients.

Coculture of embryos on homologous endometrial cells in patients with repeated failures of implantation.

OBJECTIVE: To evaluate the value of coculture of embryos on endometrial cells in patients with repeated failures of implantation. DESIGN: A retrospective comparison of pregnancy rates between IVF-ET with coculture and standard culture methods. PATIENTS: Ninety patients with repeated failures of transfer (range 4 to 11) underwent IVF-ET for a variety of disorders. METHOD: Embryos were cocultured on homologous endometrial cells and transferred on day 4 after retrieval of oocytes. RESULTS: The overall pregnancy rate for these patients was 21% per transfer versus 8% in previous IVF-ET cycles. A higher percentage (28%) was obtained for women < 39 years of age or on transfer of at least one morula (32.5% pregnancy per transfer). CONCLUSION: Coculture of embryos on homologous endometrial cells is both safe and ethical. It appears to be a valuable approach for the selection of a good quality embryo before transfer. The technique should prove to be of benefit to patients with repeated failures of implantation and also may be of value for assessing the respective responsibility of endometrium and embryo in these repeated failures. However, the mechanisms underlying this improvement need to be determined to simplify the procedure.

[Intra-uterine insemination with activated sperm. Results of conception compared in the various types of infertility in spouses]. / Insémination intra-utérine de sperme capacité. Efficacité conceptionnelle comparée dans différents types d'infertilité du couple.

A total of 180 infertile couples were treated with intra-uterine insemination of homologous capacitated sperm. The fertility disorder was: a cervical factor in 80 couples (44.4%), a male factor in 68 others (37.8%) and unexplained infertility in 32 couples (17.8%). All the patients received ovarian stimulation with HMG, and with ultrasonographic monitoring. Insemination was performed when the diameter of the dominant follicle reached 18 mm, and HCG 5,000 UI was given on the same day; another insemination was performed 40 hours later if the dominant follicle was still present. The 0.5 ml insemination sample was prepared through a migration-capacitation procedure into Earles medium which yielded 15% of the total motile spermatozoa in the ejaculate. A total of 22 pregnancies were recorded (12% of the couples) in 659 therapeutic cycles; the results however differed according to the infertility disorder: 18.8% of pregnancies in the cervical factor group, 15.6% in the unexplained infertility group and 2.9% only in the male factor group. The lowest number of inseminated motile spermatozoa for pregnancy to occur was 0.4 million. A mild hyperstimulation syndrome was noted in 28 cycles (3.1%); no complications of infectious or immunologic origin occurred. It appears that a procedure which results in a satisfactory pregnancy rate when the sperm is normal (cervical or unexplained infertility) yields poor conceptional results when the semen is abnormal. In cases where the male factor is predominant, intra-uterine insemination should not be performed in the periovulatory period but at ovulation time, and therefore requires either an accurate detection of the LH peak or complete hormonal and sonographic assessment in a stimulated cycle.

[Peritoneal gliomatosis associated with a mature teratoma of the ovary]. / Gliomatose péritonéale associée à un tératome mature de l'ovaire.

Peritoneal or/and omental implants composed of mature glial tissue is a rare complication of ovarian teratomas. A few cases have been previously reported, and one more case is described. The glial nature of the implants is proved by the presence of glial fibrillary acidic protein. The previous reports of long survival indicate that occurrence of this peritoneal gliomatosis does not alter the prognosis and that therapy directed at the peritoneal implants of mature glia is not required for cure.

[Baso- and spinocellular Pinkus fibroepithelial tumor]. / Une tumeur fibro-épithéliale de Pinkus baso- et spino-cellulaire (TFEP).

A seventy-eight-year-old man presented with a moist proliferating tumor of the back which arose six months earlier amidst numerous verrucae seborrheic. The tumor's size was 20 X 28 mm. Two different aspects were found upon histologic examination. One was a Pinkus fibroepithelial tumor with foci of basal cell proliferation, stromal changes with fibrosis, and lymphocytic infiltration. Adjacent to this tumor was a squamous-cell carcinoma. Foci of squamous-cell carcinoma were also found within the Pinkus epithelial tumor.

[Cutaneous symptoms of thrombocytemia (author's transl)]. / Manifestations cutanées des thrombocytémies

By the study of 4 personal cases and a review of the literature, the authors describe the symptoms which may complicate and even reveal an essential thrombocythemia. They are: painful symptoms which indicate a permanent or paroxystic vasculomotor syndrome by their localization and their course: -erythematous lesions of an inflammatory livedo type located on the legs and blue-red reticular spots on the sole of the foot: --occurrence of gangrene on finger ends or of necrotic ulcerations of the legs. Etiological conditions, exploration of primary hemostasis, physiopathology of the troubles are described. As for therapeutics the antiaggregants have a suspensive effect on the symptoms but only the control of the hematological status may allow recovery.